Error in my tune-$100 to find it for someone

[LS1_Dragster]

67SS509 - Are you still running a version my tune? If I'm not mistaken, you are so references back to your old tune are not valid.

Lee

[98 tigershark]

Thats a very good point but the map sensor is mounted in a different position on the carb type manifold, Correct?. Even though a little, it is still in need of some corrections I have been told. I looked into putting one of those on my L92 427, A very cool look. But the MAP sensor is in a different Position as I recall and might need and adjustment somewhere in the tune and the Diagnostics areas. Thats what I was told. It does not take much to change things. Remember the VE needs the exact same Map to be acurate and that also goes to the G/S for the timing. This is important on all OS whether new or older!!
please let me know as I really like that setup and am curious about the Map KPA/GS and timing issues.
Good luck,
98 tigershark

67SS509 - Are you still running a version my tune? If I'm not mistaken, you are so references back to your old tune are not valid.

Lee

[LS1_Dragster]

The MAP sensor is just reading vacuum, you could have a 4 foot vacuum line feeding it! I suppose there could be a very small time variance in the vacuum reaching the sensor but I just don't see how it could ever effect the tune much. The manifold and throttle body design on the other hand will change your VE settings for sure.

I'm sure he copied over all his fuel/air tables otherwise it wouldn't run very well. When I suggested he use my tune it was mainly for the trans segment, trying to eliminate any issues with that.

[98 tigershark]

Hey LS1_Dragster,

The Map sensor is almost solely based off of the #8 Cylinder with the Carb style intake. Where as the Stock manifold it is the entire manifold. The VE is calculated with Map and thus so is the G/S for timing. So the map position in the manifold is some what critical as with the LS7 carb style intake, it is mainly reading Map on the #8 cylinder. Thats a pretty big change not to make an adjustment for.
When I looked into doing that, I was told about that issue and to be aware that it may change things, especially timing, whether SD or with MAF. It may also take awhile for the PCM to learn this new positions readings.
I am not saying that is for sure the issue here but I have not seen anything in this thread to adjust for that. If #8 is not running well and the other Cylinders are the Map could be way off and really mess with things also, just as an example.
Regards,
98 tigershark

The MAP sensor is just reading vacuum, you could have a 4 foot vacuum line feeding it! I suppose there could be a very small time variance in the vacuum reaching the sensor but I just don't see how it could ever effect the tune much. The manifold and throttle body design on the other hand will change your VE settings for sure.

I'm sure he copied over all his fuel/air tables otherwise it wouldn't run very well. When I suggested he use my tune it was mainly for the trans segment, trying to eliminate any issues with that.

[LS1_Dragster]

when your mentioning carb style intake, are your referring to mine or the original posters?

I drilled and tapped my feed to the common plenum.

I looked at the GM intake and it looks like you would have to do the same, so why would anyone drill and tap into the #8 runner?

[98 tigershark]

Does the person we are discussing in this threat have the GM LS7 Carb style intake? If so they provide the Map sensor hole on the #8 runner. Look at the 2008 GM performance parts catalog on page 293. You will see what I mean.
But that is a good question. He is using the GM LS7 Carb Intake right?
I think it is very cool that you use those type of intakes.
Let me know.
thanks,
98 tigershark

when your mentioning carb style intake, are your referring to mine or the original posters?

I drilled and tapped my feed to the common plenum.

I looked at the GM intake and it looks like you would have to do the same, so why would anyone drill and tap into the #8 runner?

[LS1_Dragster]

I just saw a picture of it and 2 things come to mind:

1) Since this is a carbureted manifold GM no doubt meant that as a brake booster port
2) If someone was to convert that to fuel injection then most likely they would drill a port in the common plenum. or use a port on the throttle body.

I really don't know how he has it set up but the worst that could happen is getting pulses of vacuum but that doesn't appear to show in the logs.

I guessing the problem is still with voltage/current to the coils. I can imagine that the relay can easily bounce the contacts, loose ground and flutter the contacts and just plain not handling the current by either being to small to handle the current, dirty contacts or just plain bad. I would ditch the relay in a heartbeat to see if it's the problem.

[98 tigershark]

I have a good connection so I will call and get back to you as I am certain the pulses you mentioned were discussed as one of the issues w/timing. Again the VE uses Map to get the G/S and any pulses can play havoc with timing.
But I will check, can we find out where the Map sensor is in this case. I would bet that it is the #8 cylinder hole. But that is a guess.
Thanks LS1_Dragster.
98 tigershark

I just saw a picture of it and 2 things come to mind:

1) Since this is a carbureted manifold GM no doubt meant that as a brake booster port
2) If someone was to convert that to fuel injection then most likely they would drill a port in the common plenum. or use a port on the throttle body.

I really don't know how he has it set up but the worst that could happen is getting pulses of vacuum but that doesn't appear to show in the logs.

I guessing the problem is still with voltage/current to the coils. I can imagine that the relay can easily bounce the contacts, loose ground and flutter the contacts and just plain not handling the current by either being to small to handle the current, dirty contacts or just plain bad. I would ditch the relay in a heartbeat to see if it's the problem.

[LS1_Dragster]

Also, as far as timing goes especially under WOT the timing for most people is set to a number such as 27 from 80-100KPA across the board, in this case timing would never ever change even if the MAP bounced all over the place as long as it bounced between 80 and 100 it would still be 27. Again, his logs showed a nice steady 24 in the first log and 27 in the second log. Since same principal applies to the fuel maps.

If I'm wrong on any of this people please chime in and let me know! I'm just talking out loud here....

[98 tigershark]

If he is using the Map hole on the GM manifold that is the problem. It fits everything including the Voltage issues. This is from GM directly. The placement of the Map is critical and again fits all of the symptoms GM or other brand. Even the WOT timing and voltages is affected so says GMPP.
Please find out as I have a permanent solution.
Thanks,
98 tigershark